Halogenated esters

ABSTRACT

Compounds of formula I wherein R 1  and R 2  are haloalkyl or halo, X is O, S, S(O), SO 2  or NR 4  where R 4  is H or alkyl, R 3  is alkyl and n is 1 to 4, and compositions comprising them, useful as insecticides. ##STR1##

This application is a continuation-in-part of copending Application Ser.No. 211,943 filed Dec. 1, 1980, the disclosure of which is hereinincorporated by reference.

This invention relates to novel cyclopropane derivatives useful asinsecticides, to processes for their preparation, to compositionscomprising them and to methods of combating insect and similarinvertebrate pests using them.

Certain naturally occurring esters of cyclopropane carboxylic acids havelong been known to possess insecticidal properties, but these compoundshave been too easily degraded by ultra violet light to be of much use inagriculture. Several groups of synthetic compounds based on cyclopropanecarboxylic acids (for example those disclosed in British PatentSpecification Nos. 1,243,858 and 1,413,491) have been evaluated in anattempt to discover compounds of sufficient light stability for use asgeneral agricultural insecticides.

A particularly useful group of such compounds is that disclosed inBritish Patent Specification No. 2,000,764 and U.S. Pat. No. 4,183,948.These compounds combine good light stability with excellent contact andresidual insecticidal properties, but, in common with the compoundsdescribed in British Patent Specification Nos. 1,243,858 and 1,413,491,they possess little or no fumigant activity. A further group ofcompounds, halobenzyl esters of3-(2,2-dihalovinyl)-2,2-dimethylcyclopropane carboxylic acids, isdescribed in U.S. Pat. No. 4,183,950 as having insecticidal propertiesbut there is no indication that the compounds possess fumigant activity.

The present invention relates to certain novel benzyl esters of3-(2,2-dihalovinyl)-2,2-dimethylcyclopropane carboxylic acids and3-(2-halo(ortrifluoromethyl)-3,3,3-trifluoropropenyl)-2,2-dimethylcyclopropanecarboxylic acids with an extremely high level of insecticidal andacaricidal activity which may be used not only as contact or residualinsecticides but also as fumigant insecticides.

Accordingly this invention provides compounds of formula: ##STR2##wherein R¹ and R² are each selected from methyl, halomethyl, and halo; Xis oxygen, sulphur, sulphinyl, sulphonyl or a group NR⁴ where R⁴represents hydrogen, lower alkyl or lower carboxylic acyl; R³ is loweralkyl, lower alkenyl, phenyl or benzyl, and additionally R³ may behydrogen when X is a group NR⁴ ; and n has a value from one to four, andeach of m and p has the value zero or one.

The term "lower" is used herein in relation to "alkyl", "alkenyl" and"carboxylic acyl" groups to indicate such groups containing up to sixcarbon atoms, although such groups containing up to four carbon atomsare generally preferred.

In a preferred aspect the invention provides compounds of formula:##STR3## wherein R¹ and R² are both methyl, chloro or bromo, or one ofR¹ and R² is fluoro or chloro and the other is trifluoromethyl, and R isalkoxymethyl of up to 4 carbon atoms in the alkoxy moiety,alkylthiomethyl of up to 4 carbon atoms in the alkylthio moiety,phenoxy, or dialkylaminomethyl of up to 4 carbon atoms in each alkylmoiety. Amongst this group of compounds there are especially preferredthose wherein R¹ and R² are both chloro, or one of R¹ and R² is chloroand the other is trifluoromethyl, and R is methoxymethyl, ethoxymethyl,n-propoxymethyl, phenoxymethyl, diethylaminomethyl or ethylthiomethyl. Ris preferably in the 4-position with respect to the cyclopropane estergroup.

Particular compounds according to the invention as defined by formula IAabove include those set out in Table I herein in which the meanings forR¹, R² and R are given for each compound.

                  TABLE I                                                         ______________________________________                                        Compound                                                                      No.         R.sup.1  R.sup.2                                                                              R                                                 ______________________________________                                        1           CF.sub.3 Cl     4-CH.sub.2 OCH.sub.3                              2           CF.sub.3 Cl     4-CH.sub.2 OC.sub.2 H.sub.5                       3           CF.sub.3 Cl     4-CH.sub.2 OC.sub.3 H.sub.7 (n)                   4           Cl       Cl     4-CH.sub.2 OCH.sub.3                              5           CF.sub.3 Cl     4-CH.sub.2 OC.sub.6 H.sub.5                       6           CF.sub.3 Cl     4-CH.sub.2 SC.sub.2 H.sub.5                       7           CF.sub.3 Cl     4-CH.sub.2 N(C.sub.2 H.sub.5).sub.2               8           Cl       Cl     4-CH.sub.2 OC.sub.2 H.sub.5                       9           Cl       Cl     4-CH.sub.2 OCH.sub.2 CH═CH.sub.2              10          CF.sub.3 Cl     4-CH.sub.2 OCH.sub.2 CH═CH.sub.2              11          CF.sub.3 Cl     4-CH.sub.2 N(CH.sub.3).sub.2                      12          CF.sub.3 Cl     4-CH.sub.2 SO.sub.2 C.sub.2 H.sub.5               13          CF.sub.3 Cl     4-CH.sub.2 NHCH.sub.3                             14          CF.sub.3 Cl     4-CH.sub.2 NHC.sub.2 H.sub.5                      15          CF.sub.3 Cl     4-CH.sub.2 SCH.sub.3                              16          CF.sub.3 Cl     4-CH.sub.2 S(O)CH.sub.3                           17          CF.sub.3 F      4-CH.sub.2 OCH.sub.3                              ______________________________________                                    

It will be appreciated by those skilled in the art that the compoundsrepresented by formula I are capable of existing in various geometricaland stereoisomeric forms. Thus there may be cis and trans isomersarising from the substitution pattern of the cyclopropane ring, and E-and Z-isomers arising from the substituted vinyl group when R¹ is notidentical with R². In addition two of the three carbon atoms of thecyclopropane are capable of existing in either R- or S-configurationssince they are asymmetrically substituted. Within the group of compoundsrepresented by Formula I the cis isomers usually have betterinsecticidal properties than the trans isomers or the mixture of cis andtrans isomers; the (+)-cis isomers being particularly preferred.

A particularly useful single isomer of a compound according to theinvention is the 4-methoxymethyltetrafluorobenzyl ester of(+)-cis-3-(Z-2-chloro-3,3,3-trichloroprop-1-en-yl)-2,2-dimethylcyclopropanecarboxylic acid, which is believed to have the (1R,3R) configuration inthe cyclopropane ring.

The compounds of the invention according to Formula I are esters and maybe prepared by conventional esterification processes, of which thefollowing are examples.

(a) An acid of formula: ##STR4## where Q represents the hydroxy groupand R¹ and R² have any of the meanings given hereinabove, may be reacteddirectly with an alcohol of formula: ##STR5## where X, R³ and m have anyof the meanings given hereinabove, the reaction preferably taking placein the presence of an acid catalyst, for example, dry hydrogen chloride.

(b) An acid halide of formula II where Q represents a halogen atom,preferably a chlorine atom, and R¹ and R² have any of the meanings givenhereinabove, may be reacted with an alcohol of formula III, the reactionpreferably taking place in the presence or a base, for example,pyridine, alkali metal hydroxide or carbonate, or alkali metal alkoxide.

(c) An acid of formula II where Q represents the hydroxy group or,preferably, an alkali metal salt thereof, may be reacted with halide offormula: ##STR6## where Q¹ represents a halogen atom, preferably thebromine or chlorine atom, X, R³ and n have any of the meanings givenhereinabove, or with the quaternary ammonium salts derived from suchhalides with tertiary amines, for example pyridine, or trialkyl aminessuch as triethylamine.

(d) A lower alkyl ester of formula (II) where Q represents a loweralkoxy group containing up to six carbon atoms, preferably the methoxyor ethoxy group, and R¹ and R² have any of the meanings givenhereinabove, is heated with an alcohol of formula III to effect atransesterification reaction. Preferably the process is performed in thepresence of a suitable catalyst, for example, an alkali metal alkoxide,such as sodium methoxide, or an alkylated titanium derivative, such astetramethyl titanate.

All of these conventional processes for the preparation of esters may becarried out using solvents and diluents for the various reactants whereappropriate, and may be accelerated or lead to higher yields of productwhen performed at elevated temperatures or in the presence ofappropriate catalysts, for example phase-transfer catalysts.

The preparation of individual isomers may be carried out in the samemanner but commencing from the corresponding individual isomers ofcompounds of formula II. These may be obtained by conventional isomerseparation techniques from mixtures of isomers. Thus cis and transisomers may be separated by fractional crystallisation of the carboxylicacids or salts thereof, whilst the various optically active species maybe obtained by fractional crystallisation of salts of the acids withoptically active amines, followed by regeneration of the optically pureacid. The optically pure isomeric form of the acid (or its equivalentacid chloride or ester) may then be reacted with the appropriate alcoholto produce a compound of formula I in the form of an individually pureisomer thereof.

The preparation of the compounds of formula II wherein Q is hydroxy,alkoxy or halo, and R¹ and R² are as defined hereinabove, useful asintermediates in the preparation of the compounds of the invention, isfully described in British Patent Specification No. 2,000,764 and inU.S. Pat. No. 4,183,948, or British Patent Specification No. 1,413,491.

The compounds of formulae III are believed not to have been describedbefore. In a further aspect therefore the invention provides compoundsof formula III wherein X, R³ and n have any of the meanings given forthe corresponding compounds of formula I, including, in particular thoseset out in Table II below which corresponds to the formula:

                  TABLE II                                                        ______________________________________                                         ##STR7##                                                                     Compound      X        R.sup.3                                                ______________________________________                                        A             O        CH.sub.3                                               B             O        C.sub.2 H.sub.5                                        C             O        C.sub.3 H.sub.7 (n)                                    D             O        C.sub.6 H.sub.5                                        E             S        C.sub.2 H.sub.5                                        F             NHC.sub.2 H.sub.5                                                                      C.sub.2 H.sub.5                                        G             O        CH.sub.2 CHCH.sub.2                                    H             NH       CH.sub.3                                               J             NH       C.sub.2 H.sub.5                                        K             NCH.sub.3                                                                              CH.sub.3                                               L             SO.sub.2 C.sub.2 H.sub.5                                        M             S        CH.sub.3                                               N             S(O)     CH.sub.3                                               ______________________________________                                    

The compounds of formula III may be prepared by a sequence of reactions,each stage of which is conventional in itself, such as those set forthby way of example in the following scheme. Further details of thevarious reactions involved are fully illustrated in the Examples herein.##STR8##

When the processes for preparing the compounds of Formula I areperformed using intermediates which are themselves mixtures of isomersthe products obtained will also be mixtures of isomers. Thus, theproduct would be a mixture of (+)-cis and (+)-trans isomers (perhapswith one form predominating) if the intermediate acid or acid derivativewas used in the form of a mixture of (+)-cis and (+)-trans isomers. If asingle isomer, of the acid, e.g. the (+)-cis isomer with Z-configurationin the 2-chloro-3,3,3-trifluoropropenyl group, was used, the productwould also be the single isomer of that stereochemical configuration, ora pair of isomers if there is an asymmetric carbon atom in the alcoholmoiety.

In order to avoid confusion the products obtained by the processesdescribed in the Examples herein are referred to as Products I to XV,each product being defined in terms of isomeric composition withreference to the compounds of Table I as follows:

Product I: 4-methoxymethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 1, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product II: 4-ethoxymethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 2, Table I) consisting of 100 w/w of the(±)-Z-cis isomer.

Product III: 4-n-propoxymethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 3, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product IV: 4-methoxymethyltetrafluorobenzyl3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate (compound No.4, Table I) consisting of 50% w/w of the (±)-cis isomer and 50% w/w ofthe (±)-trans isomer

Product V: 4-phenoxymethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 5, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product VI: 4-ethylthiomethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 6, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product VII: 4-diethylaminomethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 7, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product VIII: 4-dimethylaminomethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 11, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product IX: 4-ethanesulphonylmethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 12, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product X: 4-methylaminomethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 13, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product XI: 4-ethylaminomethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 14, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product XII: 4-methylthiomethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 15, of Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product XIII: 4-methanesulphinylmethyltetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-nyl)-2,2-dimethylcyclopropanecarboxylate (compound no. 16, of Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product XIV: 4-methoxymethyltetrafluorobenzyl3-(2,3,3,3-tetrafluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 17, Table I) consisting of 100% w/w of the(±)-Z-cis isomer.

Product XV: 4-methoxymethyltetrafluorobenzyl3-(2,3,3,3-tetrafluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (compound no. 17, Table I) consisting of a mixture of ca.10% w/w of the (±)-Z-cis isomer and ca. 90% w/w of the (±)-Z-transisomer.

The compounds of formula I may be used to combat and controlinfestations of insect pests and also other invertebrate pests, forexample, acarine pests. The insect and acarine pests which may becombatted and controlled by the use of the invention compounds includethose pests associated with agriculture (which term includes the growingof crops for food and fibre products, horticulture and animalhusbandry), forestry, the storage of products of vegetable origin, suchas fruit, grain and timber, and also those pests associated with thetransmission of diseases of man and animals.

In order to apply the compounds to the locus of the pests they areusually formulated into compositions which include in addition to theinsecticidally active ingredient or ingredients of formula I suitableinert diluent or carrier materials, and/or surface active agents. Thecompositions may also comprise another pesticidal material, for exampleanother insecticide or acaricide, or a fungicide, or may also comprise ainsecticide synergist, such as for example dodecyl imidazole, safroxan,or piperonyl butoxide.

The compositions may be in the form of dusting powders wherein theactive ingredient is mixed with a solid diluent or carrier, for examplekaolin, bentonite, kieselguhr, or talc, or they may be in the form ofgranules, wherein the active ingredient is absorbed in a porous granularmaterial for example pumice, gypsum or corn cob granules. Granules areparticularly useful for combating soil borne insect pests, such as rootworms of the genus Diabrotica, cutworms (Agrotis spp.) and wireworms(Agriotis spp.). Preferably, the granules contain from 1 to 2.5% byweight of the active ingredient, which is absorbed onto the granule by,for example, spraying the granules with a solution of the activeingredient in a volatile solvent which is subsequently evaporated fromthe surface of the granules. Such solutions may contain otheringredients, for example a resin to regulate the rate of release of theactive ingredient from the granules, or to help prevent prematuredisintegration of the granules. Granules may be applied to the soileither in a band between the furrows defining the crop rows, orbroadcast, and may if desired be lightly incorporated in the soil, orthey may be placed in the furrows themselves at the time of planting thecrop. Application of granules at a rate of from 5 to 25 lb/acre(approximately 5 to 25 kg/ha) is usually sufficient to control thepests, and a preferred rate is within the range 8 to 15 lb/acre(approximately 8 to 15 kg/ha) based on the active ingredient.

Alternatively the compositions may be in the form of liquid preparationsto be used as dips or sprays, which are generally aqueous dispersions oremulsions of the active ingredient in the presence of one or more knownwetting agents, dispersing agents or emulsifying agents (surface activeagents).

Wetting agents, dispersing agents and emulsifying agents may be of thecationic, anionic or non-ionic type. Suitable agents of the cationictype include, for example, quaternary ammonium compounds, for examplecetyltrimethyl ammonium bromide. Suitable agents of the anionic typeinclude, for example, soaps, salts of aliphatic monoesters or sulphuricacid, for example sodium lauryl sulphate, salts of sulphonated aromaticcompounds, for example sodium dodecylbenzenesulphonate, sodium, calciumor ammonium lignosulphonate, or butylnaphthalene sulphonate, and amixture of the sodium salts of diisopropyl- and triisopropylnaphthalenesulphonates. Suitable agents of the non-ionic type include, for example,the condensation products of ethylene oxide with fatty alcohols such asoleyl alcohol or cetyl alcohol, or with alkyl phenols such as octylphenol, nonyl phenol and octyl cresol. Other non-ionic agents are thepartial esters derived from long chain fatty acids and hexitolanhydrides, the condensation products of the said partial esters withethylene oxide, and the lecithins.

The compositions may be prepared by dissolving the active ingredient ina suitable solvent, for example, a ketonic solvent such as diacetonealcohol, or an aromatic solvent such as trimethylbenzene and adding themixture so obtained to water which may contain one or more knownwetting, dispersing or emulsifying agents. Other suitable organicsolvents are dimethyl formamide, ethylene dichloride, isopropyl alcohol,propylene glycol and other glycols, diacetone alcohol, toluene,kerosene, white oil, methylnaphthalene, xylenes and trichloroethylene,N-methyl-2-pyrrolidone and tetrahydro furfuryl alcohol (THFA).

The compositions to be used as sprays may also be in the form ofaerosols wherein the formulation is held in a container under pressurein the presence of a propellant such as fluorotrichloromethane ordichlorodifluoromethane.

The compositions which are to be used in the form of aqueous dispersionsor emulsions are generally supplied in the form of a concentratecontaining a high proportion of the active ingredient or ingredients,the said concentrate to be diluted with water before use. Theseconcentrates are often required to withstand storage for prolongedperiods and after such storage, to be capable of dilution with water toform aqueous preparations which remain homogenous for a sufficient timeto enable them to be applied by conventional spray equipment. Theconcentrates may contain 10-85% by weight of the active ingredient oringredients. When diluted to form aqueous preparations such preparationsmay contain varying amounts of the active ingredient depending upon thepurpose for which they are to be used. For agricultural or horticulturalpurposes, an aqueous preparation containing between 0.0001% and 0.1% byweight of the active ingredient is particularly useful.

In use the compositions are applied to the pests, to the locus of thepests, to the habitat of the pests, or to growing plants liable toinfestation by the pests, by any of the known means of applyingpesticidal compositions, for example, by dusting or spraying.

The compositions of the invention are very toxic to wide varieties ofinsect and other invertebrate pests, including, for example, thefollowing:

Aphis fabae (aphids)

Megoura viceae (aphids)

Aedes aegypti (mosquitoes)

Dysdercus fasciatus (capsids)

Musca domestica (houseflies)

Pieris brassicase (white butterfly, larvae)

Plutella maculipennis (diamond back month, larvae)

Phaedon cochleariae (mustard beetle)

Telarius cinnabarinus (carmine spider mite)

Aonidiella spp. (scale insects)

Trialeuroides spp. (white flies)

Blattella germanica (cockroaches)

Spodoptera littoralis (cotton leaf worm)

Chortiocetes terminifera (locusts)

Diabrotica spp. (rootworms)

Agrotis spp. (cutworms)

The compounds of formula I and compositions comprising them have shownthemselves to be particularly useful in controlling lepidopteran pestsof cotton, for example Spodoptera spp. and Heliothis spp. The fumigantproperties of the compounds enable them to be used to combat pests whichinhabit the soil, for example Diabrotica spp. They are also excellentknock down agents and as such may be used in conjunction with otherinsecticides to combat public health pests such as flies. They are alsovery useful in combatting insect and acarine pests which infest domesticanimals, such as Lucilia sericata, and ixodid ticks such as Boophilusspp., Ixodes spp., Amblyomma spp., Rhipicephalus spp., and Dermaceutorspp. They are effective in combatting both susceptible and resistantstrains of these pests in their adult, larval and intermediate stages ofgrowth, and may be applied to the infested host animal by topical, oralor parenteral administration.

The following Examples illustrate the various aspects of the invention.

EXAMPLE 1

This Example illustrates the insecticidal properties of the Products Ito VII.

The activity of the products was determined using a variety of insectpests. The product was used in the form of liquid preparationscontaining 500, 100, 50 or 25 parts per million (p.p.m.) by weight ofthe product. The preparations were made by dissolving the product in amixture of solvents consisting of 4 parts by volume of acetone and 1part by volume of diacetone alcohol. The solutions were then dilutedwith water containing 0.01% by weight of a wetting agent sold under thetrade name "LISSAPOL" NX until the liquid preparations contained therequired concentration of the product. "Lissapol" is a Registered TradeMark.

The test procedure adopted with regard to each pest was basically thesame and comprised supporting a number of the pests on a medium whichwas usually a host plant or a foodstuff on which the pests feed, andtreating either or both the pests and the medium with the preparations.The mortality of the pests was then assessed at periods usually varyingfrom one to three days after the treatment. Details are given in TableIII.

The results of the tests are given in Table IV for each of the productsI to VII at the rate in parts per million given in the second column asa grading of mortality on a scale of 0-9 wherein:

0 represents less than 10% mortality;

1 represents from 10 to 19% mortality;

2 represents from 20 to 29% mortality;

3 represents from 30 to 39% mortality;

4 represents from 40 to 49% mortality;

5 represents from 50 to 59% mortality;

6 represents from 60 to 69% mortality;

7 represents from 70 to 79% mortality;

8 represents from 80 to 89% mortality;

9 represents from 90 to 100% mortality;

In Table IV the pest organism used is designated by a letter code andthe pest species, the support medium or food, and the type and durationof test is given in Table III.

                  TABLE III                                                       ______________________________________                                                              SUP-                                                    CODE                  PORT                                                    LETTERS               ME-      TYPE   DURA-                                   (Table                DIUM     OF     TION                                    IV)     PEST SPECIES  FOOD     TEST*  (days)                                  ______________________________________                                        MD      Musca domestica                                                                             Cotton   Contact                                                                              2                                               (houseflies - adults)                                                                       wool/                                                                         milk,                                                                         sugar                                                   SL      Spodoptera littoralis                                                                       Cotton   Residual                                                                             1                                               (cotton leaf worm -                                                                         leaves                                                          larvae)                                                               PX      Plutella xylostella                                                                         Mustard  Residual                                                                             3                                               (diamond back moth -                                                                        leaves                                                          larvae)                                                               SG      Sitophilus granarius                                                                        Grain    Contact                                                                              3                                               (grain weevil -                                                               adults)                                                               DB      Diabrotica balteata                                                                         Filter   Contact                                                                              3                                               (rootworm - larvae)                                                                         paper                                                   ______________________________________                                         *"Contact" test indicates that both pests and medium were treated and         "residual" indicates that the medium was treated before infestation with      the pest.                                                                

                  TABLE IV                                                        ______________________________________                                                 RATE   PEST SPECIES                                                  PRODUCT    (ppm)    MD     SL   PX   SG   DB                                  ______________________________________                                        I           50      9      9    9    9    9                                   II         100      9      9    9    9    9                                   III        500      9      9    9    9    9                                   IV         100      9      9    9    9    9                                   V          100      --     9    9    0    3                                   VI          50      9      9    9    9    9                                   VII        100      9      9    9    9    9                                   VIII       100      --     9    9    9    9                                   IX         100      5      9    0    0    2                                   X          100      9      9    9    0    2                                   XI         100      9      9    9    0    9                                   XII        100      9      9    9    9    9                                   XIII       100      9      0    6    0    5                                   XIV        100      9      9    9    --   9                                   XV         100      9      9    9    --   9                                   ______________________________________                                    

In further tests the products showed insecticidal activity against anumber of other species. Thus for example Product VII, showed goodaphicidal properties against Aphis fabae.

In Table V below the minimum concentration (in parts per million)required to give 100% mortality of red spider mite adults (Tetranychustelarius, SM) on French bean leaves and plant hoppers (Nilaparvatalugens, PH) on rice is given for several of the Products. A dash (--) inthis table indicates that 100% mortality was not obtained at the highestrate tested (usually 500 parts per million).

                  TABLE V                                                         ______________________________________                                                     Rate (ppm) giving                                                             100% mortality                                                   Product        SM       PH                                                    ______________________________________                                        I              100      100                                                   II             100      100                                                   III            --       500                                                   VII            --       100                                                   ______________________________________                                    

EXAMPLE 2

This Example illustrates the preparation of 2,3,5,6-tetrafluorotoluene.

A solution of n-butyllithium in hexane (1.6 M, 62.5 ml) was addeddropwise to a well stirred solution of 1,2,4,5-tetrafluorobenzene (15.0g) in dry tetrahydrofuran (150 ml) maintained at a temperature of -60°C. under an atmosphere of dry argon. When the addition was complete themixture was stirred at -45° C. for 2 hours and then methyl iodide (14.2g) was added dropwise whilst the temperature was kept at -45° C. After aperiod of 30 minutes the mixture was allowed to warm to the ambienttemperature, poured into distilled water and the mixture extracted withdiethyl ether (2×50 ml), and the extracts dried over anhydrous magnesiumsulphate. After filtering the solution was concentrated by evaporationof the solvents at atmospheric pressure. The residual oil was distilledand the fraction boiling in the range 117°-121° C. at atmosphericpressure 6.0 g) collected, identified by n.m.r. and gas chromatographicanalysis as consisting of ca. 95% of the required2,3,5,6-tetrafluorotoluene and ca. 5% of 2,3,5,6-tetrafluoro-1,4-xylene.

N.m.r. (¹ H(ppm)CDCl₃): 2.28(t,3H); 6.58-6.94 (m,1H). Infra red (liquidfilm): 3075, 1645, 1510, 1255, 1165 cm⁻¹.

EXAMPLE 3

This example illustrates the preparation of 2,3,5,6-tetrafluoro-4-toluicacid.

The product of Example 2 above (5.5 g) was mixed with diethyl ether (35ml), the mixture cooled to -70° C., and maintained at this temperaturewhilst a solution of n-butyllithium in h-hexane (1.6 M, 21 ml) wasslowly added. The mixture was stirred for a period of 1 hour duringwhich time a fine white precipitate was formed. Dry carbon dioxide gaswas then passed into the mixture for 30 minutes whilst the temperaturewas maintained within the range -70° C. to -40° C., and continued to bepassed in thereafter whilst the mixture was allowed to warm to theambient temperature.

After acidifying with dilute hydrochloric acid (6 N, 40 ml) the organicphase was separated, washed with water and dried over anhydrousmagnesium sulphate. After evaporation of the solvents under reducedpressure the residual oil (which from n.m.r. analysis was shown to be anapproximately 1:1 mixture of the desired product and pentanoic acid) wascarefully distilled under reduced pressure (water pump) using aKugelrohr apparatus, and the fraction which solidified on coolingcollected and recrystallised from toluene to yield2,3,5,6-tetrafluoro-4-toluic acid, m.p. 170° C. (0.65 g), identified byinfra red and nuclear magnetic resonance spectroscopy.

N.m.r. (¹ H(ppm)CDCl₃): 2.44 (t,3H); 11.56 (s,1H) Infra red (liquidparaffin): 3300-2450, 1710, 1650, 1460, 1070 cm⁻¹.

EXAMPLE 4

This example illustrates the preparation of 2,3,5,6-tetrafluorobenzylbromide.

A mixture of 2,3,5,6-tetrafluorotoluene (1.7 g), N-bromosuccinimide (1.9g), dry carbon tetrachloride (10 ml) and benzoyl peroxide (0.01 g) washeated at the reflux temperature for 20 hours, cooled to the ambienttemperature (ca.25° C.) filtered and the filtrate diluted with diethylether. The ethereal solution was washed with water, dried over anhydrousmagnesium sulphate and concentrated by evaporation of the solvents toyield 2,3,5,6-tetrafluorobenzyl bromide as a mobile colourless oil.

EXAMPLE 5

This Example illustrates the preparation of methyl 4-methyl2,3,5,6-tetrafluorobenzoate.

A mixture of 2,3,5,6-tetrafluoro-4-toluic acid (1.0 g), methyl alcohol(5 ml) and concentrated sulphuric acid (0.25 ml) was heated at thereflux temperature for 10 hours, cooled to the ambient temperature (ca.25° C.) and poured into iced water. The resultant mixture was extractedwith diethyl ether, the extracts washed with water, dried over anhydrousmagnesium sulphate and concentrated by evaporation of the ether underreduced pressure. The residual oil was shown by infra red analysis(liquid film: 1740 cm⁻¹) and N.m.r. spectroscopy to be the requiredmethyl 4-methyl 2,3,5,6-tetrafluorobenzoate.

EXAMPLE 6

This Example illustrates the preparation ofN,N-diethyl-2,3,5,6-tetrafluorobenzylamine.

A solution of diethylamine (0.6 g) in dry diethyl ether (2.0 ml) wasadded slowly to a stirred solution of 2,3,5,6-tetrafluorobenzyl bromide(2.0 g) in diethyl ether (30 ml) at the ambient temperature (ca. 25°C.), and the resultant mixture stirred for a further 6 hours and thenkept at the ambient temperature for a further 18 hours. After removal ofthe ether by evaporation water containing a few drops of dilutehydrochloric acid was added to the residue and the mixture obtainedwashed with ether, made basic with saturated sodium bicarbonate solutionand extracted with ether. The ethereal extracts were washed with water,dried over anhydrous magnesium sulphate and concentrated by evaporationof the ether. The residual oil was shown by infra red and N.m.r.spectroscopy to be N,N-diethyl-2,3,5,6-tetrafluorobenzylamine.

EXAMPLE 7

The procedure of Example 3 was used to convertdiethylaminomethyl-2,3,5,6-tetrafluorobenzene to4-diethylaminomethyl-2,3,5,6-tetrafluorobenzoic acid.

EXAMPLE 8

The procedure of Example 5 was used to convertdiethylaminomethyl-2,3,5,6-tetrafluorobenzoic acid to its methyl ester.

EXAMPLE 9

This Example illustrates the preparation of4-diethylaminomethyl-2,3,5,6-tetrafluorobenzyl alcohol.

Lithium aluminium hydride (50 mg) was added carefully to a stirredsolution of methyl 4-diethylamino-2,3,5,6-tetrafluorobenzoate (0.79 g)in dry diethyl ether (10 ml) at the ambient temperature. After 1 hourthe mixture was heated at the reflux temperature for 7 hours after whichthe mixture was cooled and partitioned between more ether and water. Theethereal phase was separated and combined with a further etherealextract of the aqueous phase. The combined extracts were washed withwater, dried over anhydrous magnesium sulphate, and the ether removed byevaporation under reduced pressure. The residual oil was purified bypreparative thick layer chromatography using 2 mm thick silica gel and a1:1 ether/petroleum ether mixture as eluent. The required product asobtained (after removal from the plate of the component of largest Rfvalue) by extraction of the silica with chloroform methyl alcoholmixture and identified by N.m.r. and infra red spectroscopy.

N.m.r. (CDCL₃): 1.10 (t,6H); 2.54 (q,4H); 3.75 (m,2H); 4.04 (S,1H); 4.72(m,2H) ppm.

Infra red (liquid fim): 3600-3100, 2980, 1490, 1280, 1050, 880 cm⁻¹.

EXAMPLE 10

This Example illustrates the preparation of ethyl2,3,5,6-tetrafluorobenzyl ether.

2,3,5,6-tetrafluorobenzyl bromide (2.43 g) was added to a stirredsolution of sodium (0.27 g) in ethyl alcohol (20 ml) at the amienttemperature, and the mixture stirred for a further 90 minutes. Afterkeeping at the ambient temperature for 18 hours the mixture was pouredinto an excess of water and the resultant mixture extracted three timeswith diethyl ether. The combined extracts were washed with water, driedover anhydrous magnesium sulphate and concentrated by evaporation of thevolatile portion under reduced pressure. The residual oil (1.6 g) wasshown N.m.r. and infra red spectroscopy to be the required product.

EXAMPLE 11

The procedure of Example 11 was used to prepare other compounds fromn-bromo-2,3,5,6-tetrafluorotoluene, and the appropriate hydroxy compoundas follows:

(i) n-propoxymethyl-2,3,5,6-tetrafluorobenzene

(ii) phenoxymethyl-2,3,5,6-tetrafluorobenzene.

EXAMPLE 12

The procedure of Example 3 was used to prepare the following benzoicacids from the appropriate precursors as follows:

(i) 4-ethoxymethyl-2,3,5,6-tetrafluorobenzoic acid

(ii) 4-n-propoxymethyl-2,3,5,6-tetrafluorobenzoic acid

(iii) 4-phenoxymethyl-2,3,5,6-tetrafluorobenzoic acid.

EXAMPLE 13

The procedure of Example 9 was used to reduce the appropriate benzoicacids to the following benzyl alcohols:

(i) 4-ethoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol.

N.m.r. (CDCl₃): 1.20 (t,3H); 2.82 (s,1H); 3.58 (q,2H); 4.61 (m,2H); 4.76(m,2H) ppm.

Infra red (liquid film): 3600-3100, 2980, 1490, 1290, 1060, 880 cm⁻¹.

(ii) 4-n-propoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol.

N.m.r. (CDCl₃): 0.92 (t,3H); 1.60 (q,2H); 3.46 (m,3H); 4.60 (m,2H); 4.77(m,2H) ppm.

Infra red (liquid film): 3600-3100, 2980, 1490, 1290, 1060, 880 cm⁻¹.

(iii) 4-phenoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol.

N.m.r. (CDCl₃): 2.10 (s,1H); 4.60 (m,2H); 5.10 (m,2H); 6.85-7.38 (m,5H)ppm.

Infra red (liquid film): 3600-3100, 2590, 1600, 1490, 1290, 1060, 1040,890 cm⁻¹.

EXAMPLE 14

The procedure of Example 4 was used to convert the methyl ester of2,3,5,6-tetrafluoro-4-toluic acid into methyl4-bromomethyl-2,3,5,6-tetrafluorobenzoate.

EXAMPLE 15

The procedure of Example 10 was used to prepare the following compoundsfrom methyl 4-bromomethyl-2,3,5,6-tetrafluorobenzoate and theappropriate alcohol or thiol.

(i) methyl 4-methoxymethyl-2,3,5,6-tetrafluorobenzoate.

(ii) methyl 4-ethylthiomethyl-2,3,5,6-tetrafluorobenzoate.

EXAMPLE 16

The procedure of Example 9 was used to obtain the following benzylalcohols by reduction of the appropriate methyl esters as follows:

(i) 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol.

N.m.r. (CDCl₃): 2.82 (s,1H); 3.44 (s,3H); 4.64 (s,2H); 4.86 (s,2H) ppm.

Infra red (liquid film): 3650-3000, 1650, 1490, 1280, 1080, 1050 cm⁻¹.

(ii) 4-ethylthiomethyl-2,3,5,6-tetrafluorobenzyl alcohol.

N.m.r. (CDCl₃): 1.26 (t,3H); 2.00 (s,1H); 2.54 (q,2H); 3.78 (s,2H); 4.78(s,2H) ppm.

Infra red (liquid film): 3650-3000, 1655, 1490, 1010, 945 cm⁻¹.

EXAMPLE 17

This Example illustrates the preparation of4-methoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-3-(Z-2-chloro-3,3,3-trifluoro-prop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (Product I).

A mixture of thionyl chloride (3.0 ml) and(±)-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylic acid, (0.200 g) was heated at the reflux temperature for 5hours, and then kept at the ambient temperature for 16 hours. Afterremoving the excess thionyl chloride by evaporation under reducedpressure (the last traces being removed by azeotropic distillation withtoluene) the resultant acid chloride was added to a mixture of4-methoxymethyltetrafluoro-benzyl alcohol (0.18 g), dry pyridine (0.065g) and dry toluene (10 ml), and the resultant mixture stirred at theambient temperatures for 2 hours and then stood at the ambienttemperature for a further 16 hours. After adding toluene (10 ml) themixture was washed successively with dilute hydrochloric acid (2 N, 20ml), water and saturated sodium bicarbonate solution, dried overanhydrous magnesium sulphate and concentrated by evaporation of thesolvent under reduced pressure. The residual oil was purified bypreparative thick layer chromatography (2 mm thick silica gel/chloroformeluent) to give 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate, identified by n.m.r. and infra red spectroscopy.

N.m.r. (¹ H(ppm)CDCl₃): 1.28 (s,6H); 1.90-2.36 (m,2H); 3.44 (s,3H); 4.64(s,2H); 5.30, (s,2H); 6.96 (d,1H).

Infra red (liquid film): 3080, 1735, 1650, 1490, 1135 cm⁻¹.

EXAMPLE 18

The procedure of Example 17 was used to prepare the following productsfrom either(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylic acid or(±)-cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylicacid and the appropriate benzyl alcohol.

(i) 4-ethoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

N.m.r. (CDCl₃): 1.22 (t,3H); 1.30 (s,6H); 1.90-2.27 (m,2H); 3.58 (q,2H);4.62 (m,6H); 5.22 (m,2H); 6.88 (d,1H) ppm.

Infra red (liquid film): 2980, 1730, 1650, 1490, 1290, 1200, 1135 cm⁻¹.

(ii) 4-n-propoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

N.m.r. (CDCl₃): 0.92 (t,3H); 1.30 (s,6H); 1.60 (q,2H); 1.90-2.27 (m,2H);3.46 (t,2H); 4.60 (m,2H); 5.22 (m,2H); 6.88 (d,1H) ppm.

Infra red (liquid film): 2980, 1730, 1650, 1490, 1290, 1200, 1140, 960cm⁻¹.

(iii) 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate.

N.m.r. (CDCl₃): 1.18-1.38 (m,6H); 1.58-2.36 (m,2H); 3.44 (s,3H); 4.60(s,2H); 5.24 (s,2H); 5.66, 6.14 (2d,1H) ppm.

Infra red (liquid film): 3080, 1735, 1655, 1495, 1135 cm⁻¹.

(iv) 4-phenoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

N.m.r. (CDCl₃): 1.30 (s,6H); 1.90-2.27 (m,2H); 5.10 (m,2H); 5.18 (m,2H);6.80-7.40 (m,6H) ppm.

Infra red (liquid film): 2980, 1730, 1650, 1600, 1490, 1290, 1200, 1140cm⁻¹.

(v) 4-diethylaminomethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (m.p. 75°-76° C.).

N.m.r. (CDCl₃): 1.10 (t,6H); 1.30 (s,6H); 1.90-2.27 (m,2H); 2.60 (q,4H);3.80 (m,2H); 5.28 (m,2H); 6.96 (d,1H) ppm.

Infra red (liquid parafin): 3070, 1730, 1650, 1490, 1270, 1200, 1140,1050, 960, 870 cm⁻¹.

(vi) 4-ethylthiomethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

N.m.r. (CDCl₃): 1.18-1.46 (m,9H); 1.88-2.36 (m,2H); 2.58 (q,2H); 3.82(s,2H); 5.22 (s,2H); 6.95 (d,1H) ppm.

Infra red (liquid film): 3080, 1735, 1655, 1490, 1135 cm⁻¹.

EXAMPLE 19

The procedure of Example 17 was also used to prepare the followingproducts from ester(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxyclic acid or (±)-cis or(±)-trans-3-(2,3,3,3-tetrafluoroprop-1-an-1-yl)-2,2-dimethylcyclopropanecarboxylic acid and the appropriate benzyl alcohol. The n.m.r. andinfra-red spectra of the products were consistent with the designatedstructures corresponding to the following:

(i) 4-dimethylaminomethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(ii) 4-ethanesulphonylmethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(iii) 4-methylaminomethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(iv) 4-ethylaminomethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(v) 4-methylthiomethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(vi) 4-methanesulphinylmethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(vii) 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-cis-3-(Z-2,3,3,3-tetrafluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.

(viii) 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl(±)-trans-3-(Z-2,3,3,3-tetrafluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate (contaminated with ca. 10% of the cis isomer).

I claim:
 1. A compound of formula: ##STR9## wherein R¹ and R² are bothchloro or one of R¹ and R² is chloro or fluoro and the other istrifluoromethyl and R is in the 4-position with respect to thecyclopropane ester group and is selected from alkoxymethyl,alkylthiomethyl, phenoxymethyl, alkanesulphinylmethyl,alkanesulphonylmethyl, alkylaminomethyl and dialkylaminomethyl groupscontaining up to four carbon atoms in the alkyl or alkane moiety.
 2. Acompound according to claim 1 wherein R is 4-methoxymethyl. 3.4-methoxymethyl-2,3,5,6-tetrafluorobenzyl3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropanecarboxylate.
 4. An insecticidal composition comprising an insecticidallyeffective amount of a compound according to claim 1 in association withan agriculturally acceptable diluent or carrier material.
 5. Acomposition according to claim 4 in the form of granules of inertcarrier coated or impregnated with said compound.
 6. A method ofcombating insect pests at a locus in which an insecticidally effectiveamount of a composition according to claim 4 is applied to the locus. 7.A method of combating soil dwelling insect pests in which aninsecticidally effective amount of a composition according to claim 5 isapplied to the soil.
 8. The method of claim 7 in which the pests arerootworms of the genus Diabrotica.